Data cards are used widely for identification purposes in applications ranging from financial transactions to security and access control. The data stored on a data card is often readily replicable and, therefore, people have been able to manufacture duplicate (or non-authentic) data cards with some ease. In order to combat fraud, information derived from the remanent noise characteristic of a magnetic stripe on a data card has been used to obtain a unique identifier (e.g., one that is extremely difficult to reproduce) that, like a fingerprint, can be used to uniquely authenticate a specific data card. The remanent noise characteristic is a noise-like magnetic field generated by the underlying magnetic medium of the magnetic stripe. The remanent noise characteristic does not change significantly over time and is effectively unique to a specific data card. Processes for extracting remanent noise information and for authenticating data cards using remanent noise information are disclosed in U.S. Pat. Nos. 5,365,586, 5,428,683, 5,740,244, 6,098,881, 6,431,445, 6,899,269, 7,090,130 and 7,210,627, the disclosures of which are incorporated herein by reference in their entirety.